Analysis of the performance of direct gain systems in Alexandria, Egypt

Abstract

The present paper presents an analysis of the performance of the direct gain systems using the weather data of Alexandria, Egypt (latitude 31.2°). The weather data file of Alexandria contains monthly average values of daily radiation on a horizontal surface, clearness index, ambient temperature, wind speed and relative humidity. Since TRNSYS needs hourly values of the previous parameters, the weather data generator developed at the Solar Energy Laboratory at Madison-Wisconsin is used to generate hourly data from the monthly average data available for Alexandria. TRNSYS is a transient simulation program developed at the University of Wisconsin-Madison. A numerical model is used to calculate the energy flows across the window to the building. The window model is then incorporated into TRNSYS to determine the thermal performance of the direct gain systems. The effect of the number of glazing, the building capacitance, and the night insulation resistance on the direct gain systems performance is studied. Finally, a comparison between the performance of the direct gain system and the collector-storage wall composed of concrete is carried out.